How to fix topology seams
I found a method that works to some extent, it is not perfect but I think it is the best that can be done with the topology.


Duplicate the mesh


we will use this to create a seamless version

Delete the faces where the cutout for the seat is


this is the geometry that is causing the problem



Select the edges at the ends of the hole and use the Grid Fill tool, Ctrl + F


The grid fille we fill the hole with some nice polygons, these will not look distorted



Add a subdivision surface modifier to the mesh


Select the mesh with the topology for the hole
In edit mode select the faces at the hole and a few faces and around it as well


Add the faces to a vertex group.


Add a shrink wrap modifier to the mesh with the hole


Select as the Target the mesh without the hole
Select as the Vertex Group the vertex group we created in step 8





Final Result